A study to measure the composition of exhaled air was carried out in subjects living in the highest city in the world: La Rinconada in Peru. People living at high altitude have a strongly disturbed metabolism and have to deal with major physiological disturbances. It is very likely that these subjects develop a disturbance of their redox system. It was therefore undertaken to study their ability to resist oxidative stress by measuring markers in the exhaled air. The traditional biomarkers encountered in this case are the alkanes resulting from the oxidative degradation of unsaturated fatty acids. The breath was collected on carbotrap tubes thanks to the Exp'Air sampling system. The analyses were carried out by GC-MS. In addition to some alkanes, witnesses of the particular conditions of their exposure to the low quantities of oxygen present in the air, it was discovered surprisingly the presence of a compound rarely detected in the exhaled air, limonene. Hypotheses are presented but no certainty exists as to the origin of this compound in the breath. Further studies are underway to determine the conditions and circumstances of occurrence of limonene in the exhaled air of these subjects chronically exposed to hypoxia.

NEMS based sensors open several opportunities for integrated solutions in emerging domains as chemical analysis and life science. With critical dimensions ranging between 10 and 100 nm, those devices can be made at the VLSI scale, possibly co-integrated with CMOS and are well suited for autonomous, highly sensitive or dense sensors. Several applications will be presented, as complex gas portable recognitions systems, mass spectrometry, or bio-sensors.

This article reports on a new method of monitoring nanoscale contacts in switches based on nanoelectromechanical systems, where the contact-mode switching characteristics can be recorded with the sensitive embedded piezoresistive (PZR) strain transducers. The devices are manufactured using state-of-the-art wafer-scale silicon-on-insulator technology featuring suspended silicon cantilevers and beams as switching elements and sub-100 nm thin silicon nanowires (SiNWs) as PZR transducers. Several different device configurations are studied, including mechanically 'cross'-shaped (`+'), coupled cantilever-SiNW structures, with and without local drain electrodes, and doubly clamped SiNW beams. Through detailed measurement and analysis, we demonstrate that the PZR transducers can enable detection of both mechanical and tunneling switching with multiple repeatable cycles. With the strong PZR effects in thin SiNWs, this type of device could be valuable especially for monitoring cold switching events, and when conventional direct readout of the switching events from the local gate or drain electrodes would not be efficient or sensitive, as nanoscale contacts may not be highly conductive, or may be degrading over time.

We report high-precision, ~femto-Faraday-level (1fF=10 -15 F) measurements of capacitance-voltage (C-V) characteristics of suspended and mechanically movable silicon nanowires (SiNWs) with widths down to 50nm, which are coupled to their localized side gate electrodes via nanoscale air gaps. To the best of our knowledge, this effort is the first direct measurement of C-V behavior, combined with analysis and modeling, to extract depletion layer width, within such very thin suspended SiNWs. We observe C-V responses different from those of conventional MOS capacitors and MOSFETs due to the new SiNW structures. We also find that the measured C-V behavior is sensitive to light and frequency of the AC voltage.

In this work, a comprehensive, predictive and quantitative model of a whole gas analyzer is provided in order to facilitate the design of such high performance devices. All the pre-analytical (gas separation) and analytical (detection and readout) stages have been modeled and experimentally calibrated. Heterogeneous simulations have been used to quantify the impact of the whole architecture on the output characteristic of the gas analyzer. Finally, the model of the NEMS sensor and the chromatography micro-column assembly has been experimentally validated with TEOX (toluene, ethylbenzene, octane, and xylene) gases.

L'invention concerne un systeme d'analyse de gaz comprenant, de l'amont vers l'aval : - un module (SEP) de separation d'au moins une partie des especes contenues dans le gaz a analyser, comprenant au moins une colonne micro-capillaire (GC) de chromatographie en phase gazeuse, et - un spectrometre de masse a temps de vol (TOFMS) couple audit module de separation, ledit spectrometre comprenant une source d'ions (MS1, MS2) adaptee pour ioniser au moins une partie desdites especes et emettre un faisceau d'ions, et une zone (MS4) de vol libre desdits ions, ledit spectrometre de masse (TOFMS) etant agence dans le volume d'au moins un substrat et comprenant un micro-reflectron (R) agence entre la source (MS1, MS2) et la zone de vol libre (MS4), une paroi (R1) dudit micro-reflectron comprenant une couche en un materiau resistif adaptee pour etre polarisee entre au moins deux regions de sorte a creer un gradient continu de champ electrostatique dans ledit reflectron.

This digest paper reports experimental demonstration of a new type of nanoelectromechanical device, combining contact-mode nanomechanical switching with sensitive integrated strain gauges in suspended thin (sub-100nm) silicon nanowires (SiNWs). By measuring and modeling the interesting coupling effects between mechanical strain and electrical transport in highly piezoresistive (PZR) thin SiNWs at room temperature, we demonstrate that, in both doubly-clamped SiNWs and mechanically `cross' coupled cantilever-SiNW structures, contact-mode and tunneling switching with multiple repeatable cycles can be also simultaneously monitored and read out in the SiNW PZR transducers naturally embedded in the devices. Given the strong piezoresistive effects in thin SiNWs, this type of devices offer a new approach for monitoring contact-mode operations, and may prove valuable when the nanoscale contacts are not highly conductive, or degrading over time.

We have developed arrays of nanomechanical systems (NEMS) by large-scale integration, comprising thousands of individual nanoresonators with densities of up to 6 million NEMS per square centimeter. The individual NEMS devices are electrically coupled using a combined series-parallel configuration that is extremely robust with respect to lithographical defects and mechanical or electrostatic-discharge damage. Given the large number of connected nanoresonators, the arrays are able to handle extremely high input powers (>1 W per array, corresponding to <1 mW per nanoresonator) without excessive heating or deterioration of resonance response. We demonstrate the utility of integrated NEMS arrays as high-performance chemical vapor sensors, detecting a part-per-billion concentration of a chemical warfare simulant within only a 2 s exposure period.